1. Field of the Invention
The present invention relates to a developing apparatus in an electrophotographic apparatus and more particularly relates to a developing apparatus used in such type of electrophotographic apparatus in which developing is carried out with liquid developer.
2. Description of the Prior Art
Wet roller developing process is known in the art. For example, such wet roller developing apparatus is known from U.S. Pat. No. 4,042,415 which comprises a supply roller with its lower portion being dipped into liquid developer contained in a reservoir and an upper roller having a helical groove formed on the circumferential surface thereof. The supply roller takes up the liquid developer from the reservoir and transmits it to the upper roller which supplies the liquid developer to a surface to be developed. Residual liquid developer in the helical groove of the upper roller is removed by a doctor blade disposed in contact with the upper roller.
Also, as an improved type of roller used for the above mentioned wet roller developing process there is known from Japanese Patent Application Publication No. 14,071/1966 published on Aug. 5, 1966 such developing roller which comprises a cylindrical core member, a sponge layer laid on the core member and a wire net covering the sponge layer. The core member is made of metal or insulating material and rotatably mounted on a rotary shaft. The sponge layer is made, for example, of polyurethane foam material and the wire net is of a certain predetermined mesh number.